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Expérience GANIL; International audience; A high-purity co-axial germanium detector has been calibrated in efficiency to a precision of about 0.15% over a wide energy range. High-precision scans of the detector crystal and gamma-ray source measurements have been compared to Monte-Carlo simulations to adjust the dimensions of a detector model. For this purpose, standard calibration sources and short-lived on-line sources have been used. The resulting efficiency calibration reaches the precision needed e.g. for branching ratio measurements of super-allowed beta decays for tests of the weak-interaction standard model.

Half-lives and branching ratios for the two mirror $ \beta$ decays of$^{23}$Mg and$^{27}$Si have been measured at the University of Jyvaskyla with the IGISOL facility. The results obtained, $ T_{1/2}=11.303(3)$ s and $ T_{1/2}= 4.112(2)$ s for the half-lives of$^{23}$Mg and$^{27}$Si , respectively, are 7 and 8 times more precise than the averages of previous measurements. The values obtained for the super-allowed branching ratios of$^{23}$Mg and$^{27}$Si are $ B.R.=92.18(8)\%$ and $ B.R.=99.74(2)\%$ , respectively. The result for$^{23}$Mg is three times more precise than the average of the previous measurements, while for$^{27}$Si the precision has not been improved, the average of the previous measurements being already very precise. Isospin-symmetry-breaking corrections have been calculated for the two nuclei to determine the corrected $ {F}t$ value.

SPIRAL2/DESIR; International audience; The DESIR (decay, excitation and storage of radioactive ions) facility at GANIL-SPIRAL2 will receive a large variety of exotic nuclei at low energy (up to 60 keV) with high intensities. However, the production methods of radioactive beams are non selective, limiting the purity of the beams of interest. Moreover, the high precision needed for nuclear structure and astrophysics studies using beta decay spectroscopy, laser spectroscopy and trap-based experiments at DESIR requires highly pure samples of exotic nuclei. The aim of the double-Pennig-trap mass separator PIPERADE is to deliver large and very pure samples of exotic nuclei to the different experiments in DESIR. New excitation schemes and a large inner diameter of the first trap will mitigate space charge effects to attempt trapping of up to 105 ions per pulse. The purification cycle will be performed in a few milliseconds so that short-lived nuclei can be purified. To extract the nuclides of interest from the large amount of isobaric contaminants, a resolving power of 105 is mandatory. Afterwards the ions of interest will be accumulated in the second trap until they constitute a sufficiently pure sample for the measurements. The status of the project is presented.

International audience; This paper gives a short review of the past and recent activities of the Atomic Collisions in Solids Lyon-group, in collaboration with other groups, in the field of high energy channelling. The ion-channelling programme was performed at GANIL-Caen and at GSI-Darmstadt. The electron-channelling programme started at ALS-Saclay for relativistic incident energies and was then extended to SPS-CERN for ultra-relativistic energies. The last part of this paper presents the electron-channelling experiments performed originally at ALS-Saclay, then at BTF-Frascati and more recently at LS-Saga, in order to observe the electron “internal clock” predicted in 1924 by L. de Broglie.

Anterior lumbar spine approaches may be indicated for fusion in degenerative lumbar spine disorders or to fill discal and bone gaps after fracture reduction. We present an anterior extraperitoneal approach applicable to any discal and vertebral levels from T12 to S1. The anatomic study, based on 25 cadavers, highlights retroperitoneal dissection principles for easy kidney and duodenopancreatic mobilisation and direct left anterior access to the entire lumbar spine. We established a precise description of the lumbar veins and the anastomoses between the left renal vein and hemiazygos system, in order to define different topographic and anatomic factors related to safe and easily reproducible approaches for cage or graft implementation. Independent of the level and previous intraperitoneal surgery, lumbar spine access with this approach safeguards the kidney, ureter, spleen, hypogastric plexus and duodenopancreatic system. Regarding operating time, blood-loss and possibilities for freshening and grafting, this technique seems an effective counterbalance to the difficulties and complex technology of endoscopic approaches. The clinical study includes our first 42 cases in traumatic and degenerative lesions. Avoiding the neurologic or hemorrhagic risk inherent in classical posterior lumbar interbody fusion (PLIF) techniques, it can be considered as a reasonable and valid alternative. This technique could be used in the near future for mini invasive discal prosthesis insertion.

Pelvic osteotomies were developed to increase or restructure the acetabular surface. Periacetabular osteotomies are considered the most difficult from the technical point of view and necessitate sufficient residual cartilaginous surface. Juxta-acetabular osteotomies avoid major disorganization of the pelvic framework and allow easier reorientation of the acetabulum. The authors present a technical variant that preserves the entire posterior column, as in the Ganz osteotomy. The effects on the vascularisation of the periacetabular region are strictly the same and there is no necrosis of the subchondral bone. This osteotomy is easier to perform, because of a single positioning associating two simultaneous approaches. The osteotomies are rectilinear and easy to check peroperatively by fluoroscopy thanks to this positioning. Another valuable aspect of this double approach consists of very easy correction of “automatic” unwanted retroversion due to the lowering of the acetabular roof. This unintended displacement is rarely reported in the literature, despite its anatomic evidence in 3-dimensional CT-scan reconstructions for pre- and peroperative evaluation.

De nouvelles formes analytiques pour les potentiels d'interaction atome-fullerene, fullerene-fullerene et fullerene-graphite sont obtenues a partir de distributions continues d'atomes de carbone et du potentiel interatomique de Buckingham. Celles-ci sont comparees aux potentiels C 60 -C 60 de Girifalco et C 60 -graphite de Ruoff et Hickmann resultant tous deux du potentiel de Lennard-Jones LJ(12,6). La chaleur latente de sublimation, la distance entre plus proche voisin et la compressibilite du C 60 solide calculees a partir de ces nouvelles expressions sont en bon accord avec les valeurs experimentales et avec celles obtenues a partir du potentiel de Girifalco. L'energie d'interaction du systeme Li@C 60 est egalement etudiee.

The deformations and stresses acting on the acetabular rim have not been very precisely documented. The authors present a study based on an experimental simulation of hip loading with anatomic correlations. 122 dissections were performed in order to define the anatomic aspect of the roof (and especially of Byers's “area 17”) and the intermediate area between the anterior and posterior acetabular cornua. Ten fresh cadavers were tested on the lines of previous studies on monopodal or bipodal loading. An extensometric study was performed with special attention to the transverse acetabular ligament, supra-acetabular area and obturator foramen. The area 17 of Byers is a transitional zone and the mobility of the posterior cornu is 3 times that of the anterior cornu. Resection of the acetabular ligament modifies the displacement of the posterior cornu under loading but has no influence on deformation of the oburator foramen. The biomechanical behavior of the acetabular roof in the standing position is influenced by the conditions of monopodal or bipodal loading and by femoral rotation, but a tendency to extrusion was constantly noted.

During therapeutic treatment with heavy ions like carbon, the beam undergoes nuclear fragmentation and secondary light charged particles, in particular protons and alpha particles, are produced. To estimate the dose deposited into the tumors and the surrounding healthy tissues, an accurate prediction on the fluences of these secondary fragments is necessary. Nowadays, a very limited set of double di ffential carbon fragmentation cross sections are being measured in the energy range used in hadrontherapy (40 to 400 MeV/u). Therefore, new measurements are performed to determine the double di ffential cross section of carbon on di erent thin targets. This work describes the experimental results of an experiment performed on May 2011 at GANIL. The double di ffential cross sections and the angular distributions of secondary fragments produced in the 12C fragmentation at 95 MeV/u on thin targets (C, CH2, Al, Al2O3, Ti and PMMA) have been measured. The experimental setup will be precisely described, the systematic error study will be explained and all the experimental data will be presented.

During therapeutic treatment with heavier ions like carbon, the beam undergoes nuclear fragmentation and secondary light charged particles, in particular protons and alpha particles, are produced. To estimate the dose deposited into the tumors and the surrounding healthy tissues, the accuracy must be higher than ($\pm$3% and$\pm$1 mm). Therefore, measurements are performed to determine the double differential cross section for different reactions. In this paper, the analysis of data from 12C +12C reactions at 95 MeV/u are presented. The emitted particles are detected with \DeltaEthin-\DeltaEthick-E telescopes made of a stack of two silicon detectors and a CsI crystal. Two different methods are used to identify the particles. One is based on graphical cuts onto the \DeltaE-E maps, the second is based on the so-called KaliVeda method using a functional description of \DeltaE versus E. The results of the two methods will be presented in this paper as well as the comparison between both.

En Champagne, des depts de pente stratifies crayeux connus sous le nom de ‘graveluche’ sont nombreux. Ils sont formes de debris calcaire dont la taille varie de 2 a 3 mm jusqu'a 1 a 2 cm et d'une matrice silteuse. Des lits gras alternent avec des lits maigres. Trois explications differentes ont ete proposees pour en expliquer la genese; il s'agirait soit: 1) de depots eoliens, 2) de depǒts de solifluxion, 3) de depǒts resultant d'ecoulements gravitaires mal precises. In Champagne, stratified chalky slope deposits, locally known as graveluche, are frequent. They consist of calcareous blocks, 2-3 mm to 1-2 cm in size, within a silty matrix. There is an alternation between lits gras and lits maigres (i.e. fine and coarser beds). Three explanations are proposed: eolian deposition, solifluction from upslope, and a gravity flow of some sort.

Une expression analytique approchee des facteurs de Franck-Condon pour les potentiels de Morse est obtenue a partir de leur expression exacte donnee recemment par Matsumoto et Iwamoto [J. Quant. Spectrosc. Radiat. Transfer 50, 103 (1993)]. L'approximation que nous introduisons elimine completement les fonctions gamma et polygamma qui apparaissent dans l'expression exacte de sorte que les facteurs de Franck-Condon ne font plus intervenir que des fonctions exponentielles et logarithmiques, ce qui permet de les calculer a l'aide d'un ordinateur de poche. De plus, cette nouvelle expression permet aussi d'inclure facilement les effets de 1«interaction vibration-rotation qui ont une grande influence sur la valeur des facteurs de Franck-Condon. Les resultats numeriques ainsi obtenus sont en bon accord avec les valeurs calculees par Matsumoto et Iwamoto, ainsi qu'avec celles obtenues a partir de calculs numeriques faisant intervenir les potentiels RKR (Rydberg-Klein-Rees) ou des potentiels de Morse pour les transitions electroniques suivantes:... (formule)..

The authors report a series of 41 dissections of the forearm intended to study the orientation of the fibers of the flexor carpi radialis (FCR). This shows that there is a constant torsion of the fibers of the FCR by an average of 180 degrees. Half of this torsion occurs in the forearm and half in the sheath of the FCR at wrist level. Awareness of this torsion is particularly useful surgically when the tendon is employed in ligamentoplasty, particularly after trapeziectomy. Our study of the orientation of the fibers was aimed at the ability to perform subcutaneous splitting of the fibers for use of part of the tendon.

The need to perform triple osteotomies of the pelvis passing very close to the articular surface leads to the isolation of bony fragments whose vascularisation may be precarious. To assess the risks of such surgery, we undertook an anatomic study of the vascularisation of the acetabulum in the fetus. 53 specimens were injected to study the vessels to the acetabulum and their distribution within the osteocartilaginous specimen. The acetabular a., a branch of the obturator a., gives a central pedicle distributed to the acetabular fossa, the triradiate cartilage and ending in the three primary bony components. The superior gluteal, inferior gluteal, internal pudendal and obturator aa. form a periacetabular vascular circle. The abundant vascularity of the acetabulum makes massive necrosis improbable in the child. However, there is a zone of precarious anastomosis at the anterior portion of the acetabulum.

The authors describe the distribution of the medial branches of the upper thoracic dorsal rami (T1 to T5 levels). At each level, after travelling through the erector spinae, they become superficial, and reach the apex of the spinous process of the corresponding vertebra. They then spread out laterally, innervating the skin. They can occasionally be compressed by paravertebral tendons, and this possibly contributes to certain forms of dorsal pain. Anastomosis of the dorsal cutaneous branch of the second thoracic nerve (T2) with the descending lateral branch of the accessory nerve has been observed. Its presence could explain the occasional clinical situations where there is no resultant paralysis from accidental surgical section of the latter nerve.

We have examined 203 lumbar and sacral skeletal specimens and have noted the frequent occurrence of a mamillo-accessory foramen, formed by the ossification of the mamillo-accessory ligament. The dorsal ramus of the lumbar nerve passes through this foramen. At the L5 level, this foramen is found frequently: in 26% of the cases on the left side and in 13.5% on the right. In some cases it is seen as a simple, deep notch. It is found much less frequently at L4 and almost never seen above. It is equally rare at the sacral level where it is formed by a narrowing and closure of the groove between the zygapophyseal joint and the sacral lateral mass. The authors propose that these bony foramina are a manifestation of osteoarthritic changes and that they could, in certain cases, irritate or compress the dorsal ramus along its passage.

Mise sous une forme finie du 2eme coefficient du viriel pour le potentiel intermoleculaire de Morse, B M (T) a l'aide de fonctions paraboliques cylindriques. Expressions analytiques simples pour B M (T) a partir du comportement asymptotique de ces fonctions

A Penning-trap isobar separator is currently under construction at CENBG (Bordeaux, France) and MPIK (Heidelberg, Germany) for a future installation at the SPIRAL2/DESIR facility. This device aims at purifying the radioactive ion beams from undesired species, in order to deliver highly pure samples of exotic nuclei to the different set-ups which will be installed in the DESIR hall. The present manuscript describes the context and the motivations to build such a system, the targeted characteristics, and the studies to find an efficient purification method for large samples of isobaric species.

The deformations and stresses acting on the acetabular rim have not been very precisely documented. The authors present a study based on an experimental simulation of hip loading with anatomic correlations. 122 dissections were performed in order to define the anatomic aspect of the roof (and especially of Byers's "area 17") and the intermediate area between the anterior and posterior acetabular cornua. Ten fresh cadavers were tested on the lines of previous studies on monopodal or bipodal loading. An extensometric study was performed with special attention to the transverse acetabular ligament, supra-acetabular area and obturator foramen. The area 17 of Byers is a transitional zone and the mobility of the posterior cornu is 3 times that of the anterior cornu. Resection of the acetabular ligament modifies the displacement of the posterior cornu under loading but has no influence on deformation of the oburator foramen. The biomechanical behavior of the acetabular roof in the standing position is influenced by the conditions of monopodal or bipodal loading and by femoral rotation, but a tendency to extrusion was constantly noted.

To assess the usefulness of magnetic resonance (MR) imaging in the diagnosis and clarification of the physiopathology of digital mucoid cysts.Twenty-three patients (14 women, nine men; aged 52-75 years) with mucoid cysts underwent MR imaging at 1.5 T with a local surface gradient coil. The pixel size was 117 microns in one direction. T2 relaxation times were measured. Contrast material was intravenously administered in 15 patients.All mucoid cysts had high signal intensity and sharp borders on T2-weighted images. Intracystic septa were present in nine patients (39%). Most cysts were solitary (n = 13) and/or in the proximal nail fold (n = 16). Satellite cysts were present in five patients. Nineteen patients (83%) had cysts with pedicles that extended to the joint. Osteoarthritis of the distal interphalangeal joint was present in 16 patients (70%). Five patients (22%) had multiple flattened cysts that were usually independent of the joint. In seven patients (30%), MR images showed cysts beneath the nail plate.Digital mucoid cysts may be polymorphic. MR imaging is helpful when cysts are in the nail bed.

To determine the magnetic resonance (MR) imaging features of subungual glomus tumors.Thirty-one patients with a clinical suspicion of glomus tumor and 10 control subjects underwent MR imaging at 1.5 T. MR images of normal glomus bodies of a cadaver finger were correlated with histologic slices. With a local surface gradient coil, the pixel size reached 117 microns in one direction. Relaxation times were measured. Gadoterate meglumine was injected in 19 patients.Normal glomus bodies were visualized in the reticular dermis of the nail bed. Twenty-seven of 28 pathologically confirmed glomus tumors were detected with MR imaging. A peripheral capsule was present in most tumors. The nail matrix was compressed in 13 cases. The authors were able to differentiate three subtypes of glomus tumors (vascular, solid, and myxoid) on the basis of relaxation times and enhancement characteristics. Four patients had mucoid cysts or angioma in the nail bed.MR imaging can help accurately define the location and limits of glomus tumors before excision.

The ligaments of the ankle are superficial and easily accessible at ultrasonography. Surprisingly, the reliability of this technique has never been proven. With this goal in mind, ten ankles were subjected to a ultrasono-anatomic comparison. The five principle ligamentous fascicles (three on the lateral side and two on the medial side) measured at ultrasonography and the values verified after dissection. This study shows that the ligaments of the ankle are analyzed with ultrasonography and that the measures done are valid and have a precision of 2 mm for the anterior fascicle and the lateral fascicle of the lateral ligamentous plane Due to its simplicity and its low price, ultrasonography appears to be an important method in evaluating the ligaments and the degree of seriousness of ankle sprains.

This anatomic study, based on six subjects, is aimed at a better description of the anterolateral thoracic fascia, not previously studied in its entirety. The literature describes a fascia of the pectoralis major m. continuous with that of the serratus anterior m., starting at the lateral border of the pectoralis major or pre-pectoral. The upper limits have never been studied and the lower limits are ill-defined, the aponeurosis of the pectoralis major or the pre-pectoral fascia being continuous with that of the rectus abdominis m. It is shown that this fascia, from a retropectoral origin, extends to the base of the axilla above and is stretched as bridge between the pectoralis major and latissimus dorsi mm. and the muscles of the anterolateral wall of the abdomen. This fascia has some surgical importance as a plane of coverage in the protection of mammary implants. The lack of concordance with classical anatomic accounts, the histology and the vascularisation of this fascia call for complementary studies.

Examination of the knee joint by magnetic resonance imaging (MRI) is a noninvasive technique of proven reliability as regards lesions of the menisci and ligaments [3, 4, 11]. It provides good definition of the different anatomic structures [10]. The meniscofemoral ligaments have been observed with varying frequency and may be responsible for false images [5, 16, 17]. However, it is important to detect them in cases of hypermobile discoid menisci of the ‘Wrisberg ligament type’ in order to guide the surgeon in their excision during total meniscectomy [2, 7]. We have attempted to assess the ability of MRI to visualise the meniscofemoral ligaments in correlation with an anatomic study and to identify certain anatomic pitfalls. This study will allow better investigation of the hypermobile menisci associated with the meniscofemoral ligaments. A clinical case is reported to illustrate its practical importance.

Ossifications in the caudal attachments of the ligamentum flavum were studied on 121 dried thoracic spines. Most of them were aged. Frequency increased in a caudal direction. At T12, frequency depended on the orientation of the zygapophyseal joints of T11-12 which determined the range of rotation. When they were of thoracic orientation, allowing large range of rotation, ossifications were present in 83% of cases. If orientation was lumbar, allowing poor range of rotation, ossifications became much less frequent:33%. The size of ossifications was also studied. The smaller were in T1 and T2. In T11 and T12, size also depended on the orientation of the zygapophyseal joints of T11-12. If it allowed important range of rotation, ossifications were large sized. In the opposite case, they were small sized. Ossifications of caudal attachments of ligamentum flavum appear to be a normal feature of the aged lower thoracic spine. Their frequency in a given motion segment seems to be influenced by rotational strains.

The results of an anatomic study based on 50 fresh adult cadaver upper extremities are analysed. All the arterial pedicles of each forearm muscle were counted, and each muscle was weighed. Each forearm contained an average number of 264 muscular pedicles. The relative mass fraction of each muscle was calculated, as was its "muscular vascular index" or MVI (number of pedicles divided by the weight of the muscle in grams). Half of the forearm muscles had a significant statistical relationship between their weight and their number of vascular pedicles. The other half had no statistical relationship. These two statistical muscular groups (with and without a statistical relationship) did not clearly correspond to anatomic or functional groups. No muscular group based on the average of MVI was found. Each of the 20 forearm muscle had finally its own characteristics of weight, number of pedicles, and MVI. The average MVI was 0.9 (from 0.4 to 1.8). The global muscular vascular index (GMVI) is the division of the total number of muscular pedicles of a forearm by the total muscular weight of this forearm. The average GMVI was 0.8 (from 0.4 to 1.6). In spite of its theoretical and practical limits, the MVI concept approximately reflects the high vascular density of the forearm muscles.

Etude numerique du domaine de validite et de la precision des expressions asymptotiques du premier et du deuxieme ordre a basse temperature pour le deuxieme coefficient du viriel du potentiel Le Morse, obtenues recemment par l'auteur. Les resultats montrent que l'expression asymptotique du deuxieme ordre fournit des valeurs en excellent accord avec les valeurs exactes pour les temperatures suffisamment basses

The MnO contents of lavas either decrease (0.20–0.07%) or remain constant (0.20%) during the differentiation of three alkali basalt series, respectively from continental (Mont-Dore, Chaine des Puys; French Massif Central) and oceanic (Nuku-Hiva; Marquesas Islands, Central Pacific) environments; the Mn/Fe ratios increase (0.015–0.1) or remain constant (0.02) in the same series. These variations are explained by the compositions (obtained by microprobe analysis) of the minerals fractionating during the magmatic evolution. The Mn contents are controlled by the sequence of separation of mafic silicates and Fe/1bTi oxides, whereas the Mn/Fe ratios are controlled by magnetite fractionation.

Thirty-seven dissections have shown that the skin of the low back is innervated by the lateral branches of the dorsal rami of T12 and L1 in 22 cases (60%) or T12 L1 and L2, in 10 cases (27%) or T12 L1 and L2 receiving an anastomosis from L3 in 5 cases (13%). The most medial nerve crossed the iliac crest through a rigid osseo-aponeurotic orifice located 7–8 cm from the midline which was seen compressing the nerve in 2 instances. This pattern of distribution may sometimes explain unilateral low back pain.

On the supposition that some "pseudocoxalgias" might be due to a neuralgia of the lateral rami leaving the subcostal and iliohypogastric nerves above the lateral edge of the iliac crest, the authors undertook an anatomic study of their pathways and pattern of distribution. These rami supplying the skin below the iliac crest, which they cross close together, the ramus arising from the subcostal nerve by perforating the internal and external oblique abdominal muscles, that arising from the iliohypogastric nerve a little lower, creating a bony groove palpable in thin subjects and transformed into an osseomembranous tunnel by the aponeurosis of these muscles. This arrangement may give rise to an entrapment syndrome. At this intersection, the course is either vertical or "bayonet-shaped", directly subcutaneous, and hence exposed to possible friction and microtraumata (tight clothes). The two rami are of unequal length. Frequently, the ramus arising from the subcostal nerve is short, not exceeding 10 cm, below the iliac crest, thus corresponding to the usual description. That arising from the iliohypogastric nerve descends further, passing 3 to 5 cm anterior to the great trochanter. It ends either at this level or 8 to 10 cm below. This accounts for the distribution of the pain felt when there is irritation of this ramus.

L'application de l'analyse thermogravimetrique a la determination des valeurs des parametres cinetiques de reactions heterogenes est tres repandue.

A study of 18 elbows in the cadaver allowed the medial fascia of the radial collateral ligament of the articular capsule to be clearly separated. Section of this ligament associated with that of the anterior fascia, without section of the ulnar collateral ligament always produces luxation of the elbow if it is in flexion. The integrity of the insertion surface of the epicondyles does not stop this luxation. This therefore confirms the arthrographic and operative observations recently published.

Colles' fractures with important displacement are accompanied by a subdislocation of the carpus backwards. The authors describe a radio-lunate sagittal index that measures the posterior displacement. This index should be instored during the reduction of the fracture.

The authors describe a modified radiological lateral view according to the points of tangency of the radial articular surface. The view allows the separate study of the radio-scaphoïd and the radiolunate joint spaces, which are otherwise superimposed on a classical side view. This view has a clinical interest especially when treating malunion deformities.

The metacarporetinacular fascicle, the fourth fascicle of the medial collateral metacarpotrapezial ligament, was examined in 25 anatomic specimens. It contributes to stability of the ligament and plays an important role in the pronosupination of the thumb. This role becomes determinate when the geometry of the articular surfaces is disturbed.

Manual compression of the vertebral artery is used in routine clinical practice for diagnosis of positional hemodynamic vertebro-basilar insufficiency (VBI). The supraclavicular and suboccipital areas were carefully dissected in 20 cadavers. Anatomical variations observed on dissection were compared to angiographic data from 150 patients and data from the literature. Objective results of manual compression of the vertebral artery can be obtained by sonography. In patients with VBI, such compression induces signs of reversible cerebellar or brain stem ischemia, whereas no signs are observed in patients without VBI.

Thirty-seven dissections have shown that the skin of the low back is innervated by the lateral branches of the dorsal rami of T12 and LI in 22 cases (60%) or T12 L1 and L2, in 10 cases (27%) or T12 L1 and L2 receiving an anastomosis from L3 in 5 cases (13%). The most medial nerve crossed the iliac crest through a rigid osseo-aponeurotic orifice located 7-8 cm from the midline which was seen compressing the nerve in 2 instances. This pattern of distribution may sometimes explain unilateral low back pain.